Sudden cardiac death is an unexpected natural death from cardiac causes within one hour of symptom onset. It is usually caused by underlying heart disease resulting in electrical disturbances and arrhythmias like ventricular fibrillation. Prognosis is poor, especially for out-of-hospital cardiac arrest, but early recognition and initiation of CPR, defibrillation if needed, and advanced life support can improve survival rates. Prevention focuses on risk stratification, treating underlying conditions, and devices like implantable defibrillators for high-risk patients.

1. Sudden cardiac death
Unexpected natural death
From a cardiac cause
Within 1 hour of onset of symptoms

2. SCD- pathophysiology
 Substrate-
 Atherosclerosis, scar, hypertrophy, myocarditis/pathy
 Triggers
 Increased sympathetic/decreased parasympathetic drive,
electrolyte abnormality, drugs, stress
 Functional defect
 Electrolyte shift, electrical instability, platelet aggregation,
vasoconstriction, ischemia
 Rhythm disturbance
 VT, V-fib, asystole, EMD/PEA

3. SCD- etiology
 IHD
 Hypertrophy
 Cardiomyopathy- HOCM
 Valvular/congenital heart disease
 Primary electrical abnormality- LQTS,
idiopathic VT/VF, WPW syndrome
 Drugs/Toxins

4. Cardiac arrest
Cessation of normal blood
circulation, due to impaired heart
contractility

5. Cardiac arrest- S/S
Absent pulse- carotid
Altered sensorium/LOC
Impaired respiration

6. Cardiac arrest- causes
 Thrombosis- MI
 Thromboembolism-
PE
 Tension
pneumothorax
 Tamponade-
cardiac
 Trauma
 Tablets-
drugs/toxins
 Hypovolemia
 Hypoxia
 Hydrogen ions-
acidosis
 Hyper/hypokalemia
 Hypothermia
 Hypo/hyperglycemia

7. Cardiac arrest- prognosis
Out-of-hospital- <10% discharge
In-hospital- ~15% discharge

8. Worse prognosis
 Cardiogenic shock
 Age >60 years
 No MI
 Coma on admission
 >4 shocks required for resuscitation
 Bad to worse- VFVTasystolePEA/EMD
 Comorbidities- CHF, COPD, CAD, DM, HT

9. Chain of survival
 Early recognition
 No pulse, no breathing, LOC
 Early CPR/CCR
 Earlier the better, preferably within 6 minutes
 To circulate oxygenated blood, specially to brain & heart
 Chest compression + mouth-to-mouth breaths (30:2)
chest compressions only at ~100 per minute
 Early defibrillation
 Shock with 360 joules
 Early ACLS
 Using drugs & mechanical ventilation

10. Basic life support- CPR

11. BLS- CCR

12. ACLS
 Mechanical ventilation
 Access- IV, IO, ETT
 Vasopressor- Epinephrine
(Vasopressin)
 Tachycardia- Amiodarone
 Bradycardia- Atropine
 Correct underlying abnormality

13. Prevention of cardiac arrest
 Primary prevention- risk stratification
 History- elderly >65, s/s of CHF, syncope, DM,
smoking, A-fib, pacemaker
 LVEF- specially <30%
 ECG- IVCD, prolonged QT, LBBB, AV block, A-fib,
LVH
 EPS
 Rx for patients at increased risk- aspirin, β-blockers,
statins, ACEI, Amiodarone/Sotalol, AICD

14. Secondary prevention
 Correct underlying abnormality-
e.g. revascularization-
CABG/PTCA
 Amiodarone-asymp./Sotalol-symp. CHF
 Catheter ablation of arrythmia
 AICD (automated implantable
cardioverter defibrillator)

15. AICD- indications
 LVEF <30%, in NYHA class II/III, on
optimal drug therapy, with
expected survival of >1 year
 Prior MI with non-sustained VT or
inducible VT in EPS
 HOCM, LQTS, Brugada syndrome